The present invention relates to a method for reducing the leachability of granular material, which essentially consists of an inorganic binder and a filler, which contains contaminants.
A method of this type is known from EP-A-0,208,871. With this method, a hydraulic binder is digested in water until it essentially no longer settles out, after which the aqueous colloidal solution thus obtained is mixed with a fine-particled waste material. During this mixing the water content of the mixture is adjusted such that the mixture can agglomerate. The mixture is then agglomerated and hardened. According to this method, each particle of waste material is enclosed within a layer of binder, as a result of which the leachability of the waste particles is reduced.
However, a method of this type has the disadvantage that the granular material formed still shows some degree of leachability, for example by rainwater if the granular material is dumped or by the mixing water if said granular material is used as a filler in, for example, concrete or the like.
Damage to the skin of hardened hydraulic binder can also occur during subsequent storage or handling of such material, as a result of which the leachability of the granules is increased again.